Left Ventricular Mechanics in Isolated Rheumatic Mitral Stenosis; Impact of Loading Condition on Different Parameters of the Left Ventricular Function

Background: Rheumatic mitral stenosis leads to depressed ventricular function, which is not detectable through the measurement of ejection fraction. Whether pancarditis or changes in loading condition results in subclinical Left Ventricular (LV) dysfunction has yet to be fully elucidated. Objectives: The aim of this study is to evaluate the effect of loading condition on left ventricular function. Methods: The present observational, case-control study was conducted on 104 cases who were referred to the echocardiography department including 71 patients with different severity degrees of rheumatic mitral stenosis and 33 healthy individuals with no past history of cardiac or other medical illnesses and with normal echocardiography who were matched with the cases in terms of age, gender, and body surface area. The strain, strain rate, rotation, torsion, and twist parameters of the left ventricle were measured via 2D speckle-tracking echocardiography. The data were analyzed using Kolmogorov-Smirnov test, independent student t-test, and one-way Analysis of Variance (ANOVA), as appropriated. Correlation analysis was also performed using linear regression, and the results were expressed as Pearson's correlation coefficients. Results: The LV Global Longitudinal Strain (GLS), Global Longitudinal Strain Rate (GLsr), and Global Circumferential Strain Rate (GCsr), but not Global Circumferential Strain (GCS), basal and apical rotations, twist, and torsion, were significantly lower in the subgroup with progressive mitral stenosis (17.7%, 1.07s-1, 22.85%, and 1.05s-1, respectively) compared to the healthy group (19.76%, 1.17 s-1, 24.15%, and 1.27 s-1, respectively) (P = 0.001, 0.032, 0.104, and < 0.001, respectively). Increase in the severity degree of mitral stenosis was accompanied by a significant decrease in the mentioned parameters. Conclusions: The rheumatic process led to a reduction in ventricular function, which was detectable through the measurement of the GLS, GLsr, and GCsr, but not GCS, twist, rotation, and torsional parameters of the left ventricle. As the severity of the stenosis progressed, other indices of the LV function such as rotation, twist, and torsion decreased significantly, indicating their more susceptibility to loading conditions compared to the rheumatic process per se.